Tract hemianopia resulting from traumatic distal internal carotid artery dissection

Abstract

A 29-year-old restrained driver was involved in a head-on automobile collision and incurred a closed head injury with momentary loss of consciousness. On awakening, he immediately noticed a left-sided visual field deficit. Neuro-ophthalmic examination was normal except for a left afferent pupillary defect and complete left homonymous hemianopia. Magnetic resonance imaging (MRI) showed a small crescent of abnormal signal in the distal right ICA consistent with arterial dissection (Fig. I). Magnetic resonance angiography gave normal results. There was bright signal in the right optic tract on fluidattenuated inversion-recovery sequences (Fig. 2). Examination 5 months later confirmed the pupil defect and showed nerve fibre layer dropout superiorly and inferiorly in the right eye (Fig. 3, top). There was nasal optic nerve pallor in the left eye (Fig. 3, bottom). Repeat coronal T2-weighted MRI showed interval development of atrophy of the right optic tract (Fig. 4).